1. First, use Enter to start a new line, and then find the paragraph module in the start column of the menu bar. There is a "horizontal line" button in the paragraph module, as shown in the figure below.

2. Click the "Horizontal Line" button, and then click "Horizontal Line" in the drop-down box, as shown in the figure below.

3. Insert a horizontal line into the Word document, and the setting is complete, as shown in the figure below.

4. After inserting the horizontal line, start to format the horizontal line, and click to select the horizontal line in the document, as shown in the figure below.

5. Right-click the mouse and select Format Horizontal Line in the page that appears, as shown in the following figure.

6. The horizontal line format setting page appears, as shown in the figure below.

7. Modify the corresponding values, and then click OK, as shown in the figure below.

8. The modified horizontal line is shown in the figure below.